An amino acid, particularly L-amino acid is generally crystallized, for example, by adding a large amount of a lower alcohol such as methanol or ethanol to an aqueous solution thereof, if necessary followed by concentrating and cooling the mixture, to thereby crystallize the L-amino acid. According to such a process, a finely powdered crystalline amino acid is obtained. This fine crystalline amino acid has disadvantages in that the specific volume is generally about 5.2 ml/g, thus resulting in bulkiness and that it tends to be scattered in handling, for example, in packing a capsule.
Further, with regard to the process for the preparation, among the above processes, a process which comprises adding a lower alcohol to thereby crystallize an amino acid requires the recovery of the alcohol and is attended with the loss of the alcohol, thus resulting in economical disadvantages. Furthermore, according to a process which comprises crystallizing an amino acid by neutralization, too much fine crystal will be precipitated to stir the mixture sufficiently, if insufficient attention is paid to the concentration of an L-amino acid before neutralization, the addition rate of a base or an acid and the stirring speed. According to a process which comprises crystallizing an amino acid by concentration and cooling, the growth rate of crystal is varied depending upon the rate of the concentration and the cooling, so that it is difficult to obtain a uniform crystal. Additionally, according to a process which comprises concentrating under a reduced pressure with cooling, the precipitated L-amino acid is a fine crystal, so that it forms foam and eventually flows out of a concentrator, resulting in an impossibility of concentration.